Method and apparatus for die casting



Oct. 5, 1965 SHIGEICHI DEGUCHI ETAL 3,209,419

METHOD AND APPARATUS FOR DIE CASTING Filed Dec. 28, 1964 4 Sheets-Sheet l Fig. 1

Q I VETTORS SHIGEICHI Hedi/an RINPEI Ko/KE BY mm W own/ 70 Oct. 5, 1965 SHIGEICHI DEGUCHI ETAL 3,209,419

METHOD AND APPARATUS FOR DIE CASTING Filed Dec. 28, 1964 4 Sheets-Sheet 2 T SH/GEI 0H! j e gL/ iu RINPEI Kd/KE Oct. 5, 1965 SHIGEICHI DEGUCHI ETAL 3,209,419

METHOD AND APPARATUS FOR DIE CASTING Filed Dec. 28, 1964 4 Sheets-Sheet 3 Fig.5

INVENTOR. SH/GEl'OH/ DEGUICH/ RINPEI KOIKE Oct. 5, 1965 SHIGEICHI DEGUCHI ETAL METHOD AND APPARATUS FOR DIE CASTING Filed Dec. 28, 1964 4 Sheets-Sheet 4 k \s I, 5% W F g. 5 Q0 &\\ V//////////////////////I/1 d7 2 W 50 INVEN'YDR 529 O SHlGE/OHI 0565/09;

R/NFE/ K /KE M r Wm United States Patent METHOD AND APPARATUS; FOR DllE IASTHNG Shigeichi Deguclri, Aichi-gun, Aichi, and Rinpei Koilre,

(Ihofu Mine-machi, Tokyo, Japan, assignors to Kabushikikaisha Torhai Rika Denki Siesakusho, Aichi Prefecture, Japan Filed Dec. 28, 1964, Ser. No. 421,381 6 Claims. (Cl. 2270) The present invention relates to die casting.

The present application is a continuation-in-part application of copending application Serial No. 198,663, filed May 29, 1962, for Casting Equipment, now abandoned.

The object of this invention is to provide a method and apparatus for die casting, automatically and successively, various kinds of articles characterized by the absence of sprues, runners, and gates, and not requiring a special apparatus for cutting off, after casting, excess metal, such as sprues, runners, and gates, of articles die cast by conventional arrangements.

Among the advantages of this invention is that there is no need of remelting of cut-off sprues, runners and gates as such parts are not required by the method of the present invention. Thereby the quality of articles is assured in that the articles can be cast with virgin metal only. Thus, there is no deleterious effect on the article, such as is present in many articles die-cast by conventional methods due to the intermingling of virgin and reused raw materials. As a result, the material cost is lessened and the quality of cast metal is improved.

A further reduction in the cost of casting, by the present method of the invention, is due to the lack of those excess metal portions or projections which usually must be removed from a cast article, as the invention method does not require any sprue, runner, or gate to be cut off after casting. Thus, there is no cost involved for remelting of discarded material, and neither space nor operating expense is necessary to transfer and remelt any discarded material.

In view of the above-mentioned object and other objects that may be describes hereinafter, the arrangement of each part of an apparatus, as an embodiment of the casting method of the invention, is described in the following specification and in the appended claims.

In the accompanying drawings illustrating an embodiment of the apparatus of the present invention in connection with the method thereof:

FIG. 1 is a front elevational view of apparatus embodying the invention;

FIGS. 2 to 6 are semi-diagrammatic partial longitudinal sectional views of the apparatus, showing operational conditions thereof; and

FIGS. 7 to are sectional views of some important parts of the apparatus which are chiefly related to the process of ejecting the casting from the die assembly.

Referring to the drawings, and particularly to FIGS. 1 to 6 thereof, a casting apparatus for practicing the method of the present invention includes a molten metal reservoir or pot 1 which may be heated by suitable means such as an oil burner, a gas burner, or an electric heater, the heat being used both to melt the metal and to maintain the metal molten. A cylindrical body 2 projects upwardly from the bottom wall 3 of the pot 1 and, at its lower end, communicates with a molten metal passage 4 formed on the bottom wall 3 of the pot 1. The cylindrical body 2 communicates with the molten metal passage 4 near the inner end of the latter, and a nozzle 9 is threaded into a cylindrical projection 8 extending laterally from the side wall 7 of the pot 1 and substantially axially aligned with the molten metal passage 4. A push rod 6 is disposed within the nozzle 9 in a manner described more in detail hereinafter.

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The cylindrical body 2 is always submerged within the molten metal in the pot 1, and a piston 5 is movably set in the cylindrical body 2. Suitable mechanism is provided to reciprocate the piston 5 vertically and cyclically, and reciprocation of the piston 5 either draws molten metal from the pot 1 into the molten metal passage 4 or forces molten metal from the molten met-a1 passage 4 through the nozzle 9 in a manner to be described. The push rod 6 is formed with a conically expanded portion 14a near its end, this expanded portion having an inner tapered surface 14b and an outer conical portion 10 with a cylindrical extension 12. Conical portion 10 is engageable in a discharge aperture of the nozzle 9 and its cylindrical extension 12 is engageable with an aperture 13 in a mouth plate 11.

A V-shaped groove 15 is formed on a portion of the push rod 6, and one arm 18 of a double arm lever 17, pivoted on a pin 6 as its center, has its end 19 engaged with the V-shaped groove 15. The other arm 20 is pivotally connected to one end of a link 22 by means of a pin 21. The other end of link 22 is pivotally connected to one end of a cam lever 24, pivotally mounted on a pin 23 as its center, by means of a pin 25. The other end of the cam lever 24 is in contact with a cam 27 rotating with a pin 26 as its center.

One end of a link 29 is pivotally connected to about the middle of the arm 20 of said double arm lever 17 by means of a pin 28, and the other end of link 29 is pivotally connected to one end of a lever 31, pivoted about a pin 30 as its center, by means of a pin 32. The other end of the aforementioned lever 31 is in contact with the aforementioned cam 27, and, further, a spring 33, one end of which is connected to arm 20 of double arm lever 17, is positioned between said links 29, 22.

A bushing 35 is fitted into the molten metal passage 4 and has a central passage slidably receiving the push rod 6, this central passage being closed at its inner end. The other end of the bushing 35 communicates with the interior 34 of the nozzle 9. Angularly spaced along the lower part or semi-circular portion of the cross sectional area of the bushing 35, there are bores 36 each having a circular cross section and each extending completely through the bushing 35 parallel with the axis thereof. The end 19 of the arm 18 which engages the V-shaped groove 15 of the push rod 6 extends through an opening 37 in a wall of the bushing 35. The push rod 6 is provided with a longitudinally extending groove 38.

The operation of parts thus described may be summarized as follows. When the piston 5 moves upwardly inside the cylindrical body 2, as shown in FIG. 6, molten metal is drawn from the pot 1 and to the molten metal passage 4 through the opening 37, the longitudinally extending groove 38, the interior 34 of the nozzle 9 and the bores 36 of the bushing 35. During this operation, the push rod 6 pushed outwards by one end 19 of double ended lever 17, by virtue of its conical port-ion 10, closes the discharge aperture of the nozzle 9 and, by virtue of its cylindrical extension 12, closes the aperture 13 in the mouth plate 11. When the molten metal has been drawn to the molten metal passage to the full, as shown in FIG. 3, the piston 5 is motivated to move downwardly, and the push rod 6 is retracted by the arm 18 to open the discharge aperture in the nozzle 9 and the aperture 13 in the mouth plate 11 as shown in FIG. 4. At the same time, the inner conical surface 14b of the conically expanded portion 14a of the push rod 6 closes the central passage 38 of the bushing 35 at its outer surface. Molten metal is forced by the piston 5 through the bores 36 into the interior 34 of the nozzle 9 and out through the aperture of the nozzle 9 and the aperture 13 in the mouth plate 11.

The molten metal thus forced out through the aperture 13 in the mouth plate 11 enters into the cavity of die block 39 of die assembly, directly and without any other intervening passages such as sprues, runners, and gates as in conventional casting apparatus, to form a cast article 40. At this very moment, the piston 5 does not yet reach the lowest position of its stroke and still continues to force the molten metal into the cavity of the die assembly. Then, the push rod 6 is moved toward the discharge aperture by suitably arranged action of the arm 18, and the conical portion 10 and its extension 12 thrust into the aperture of the nozzle 9 and the aperture 13 in the mouth plate 11 to close the passage thereof completely, as shown in FIG. 5. The casting is quickly cooled by water so as to rapidly extract heat from the casting. In this case, in ordinary practice, it may be feared that an accurate cast article should not be obtainable, since a half solidified body of metal would be formed inside the aperture of the nozzle 9 and inside the aperture 13 in the mouth plate 11, while cooling is effected as stated, and that this half solidified body of metal should be removed for the subsequent casting. However, by the invention method, as shown in FIG. 5 such a half-solidified body of metal will never be formed, since the conical portion 10 and its cylindrical extension 12 of the push rod 6 remove the molten metal in the apertures, either compressively into the cavity of the die assembly or backwardly into the interior 34 of the nozzle 9, by having the push rod moved, at the appropriate time of the cyclical operation, toward the nozzle 9 until the cylindrical extension 12 of the conical portion 10 of the push rod 6 reaches the extreme outer edge of the aperture 13 in the mouth plate 11, forming no half-solidified body of metal there and resulting in no sprue, runner, nor gate casting.

Referring to FIGS. 7 through 10, die block 39 is longitudinally slidable in guide 42, as shown more particularly in FIG. 8. One longitudinal surface of die block 39 bears against mouth plate 11, and the opposite longitudinal surface thereof is in contact with a core or mold part 47, as best seen in FIGS. 3 and 5. Core part 47 is displaceable away from die block 39 by operating of a lever 48a which has an end connected through a coupling or pivotal connection 48 to a threaded extension of mold part 47.

Rods 43 and 44 are mounted within die block 39, and constitute core parts of the mold. Rod 43 is disengageably secured to guide 42. Movable rod 44 is connected, through a pivotal coupling 46 engaging a threaded extension thereof, to a lever 46a. A threaded rod 43a is secured to die block 39 and is connected, through the pivotal connection 45 to the upper end of a lever 45a. The respective pivotal connections 45, 46 and 48 are adjustable longitudinally of the threaded extensions engaged thereby.

The operation of all of the various parts of the apparatus is effected by the various levers pivoted about the axis A-A' of FIG. 1. These levers are operated by cams rotating about their axis BB, driven by a motor or other driving means (not shown), and illustrated in FIG. 1.

In the operation of the invention method, after the molten metal has been injected into the cavity of the die assembly through the molten metal passage 4, the bores 36, the aperture of the nozzle 9 and the aperture 13 in the mouth plate, by downward movement of the piston 5, the core part 47 is retracted by a lever 48a pivoted by a pivot 48 about the axis AA. This releases the die block 39 for longitudinal movement along the guide 42.

The die block 39 is then moved by the lever 45a and the movable rod 43a in the direction indicated by the arrow in FIG. 8, and so the core part 43, which is secured to the guide 42, is retracted from the casting 40. As shown in FIG. 9, by movement of the lever 46a, the movable rod acting also as core part 44 is moved in the direction of the arrow and thus is also retracted from the casting 40.

Referring to FIG. 10, an ejector pin is moved into the die block 39 to eject the casting 40. The ejector pin 50 moves into the die block 39 from the rear and is operated by a lever 49 through the illustrated linkage. After retraction of pin 50, the parts return to their initial positions for repetition of the cyclical operation.

Heretofore, the casting equipment by conventional methods having sprues, runners or gates has been very complicated in construction and accurate casting has not been possible, and the quantity production of small cast goods is not easily possible as the operation thereof is quite difficult.

By contrast, with the arrangement of the present invention, molten metal from the pot 1 is injected successively and automatically from the nozzle 9, by the action of the piston 5, into a metallic die assembly positioned in operative relation with the nozzle 9. The die assembly is slidably supported on a seat so that, after having molten metal injected into the cavity thereof, the die block 39 is shifted to a predetermined position along the outer surface of the mouth plate 11, without producing any sprues, runners, or gates. Simultaneously, the core parts of the die assembly are retracted, and the cast article may be ejected by the ejector pin 50. Thus, very complicated cast articles can be produced automatically in a highly efiicient manner and by a cyclical operation.

With the invention arrangement, as the die block 39 is in flush slidable relation with the mouth plate 11, and thus easily displaceable relative to the nozzle 9, the construction of the equipment is greatly simplified and movement of the die block from the charging position to the ejection position can be effected smoothly by means of the several levers. In this connection the rods, such as 43 and 44, are part of the core assembly. Thus, the invention apparatus has the advantage of providing cast goods without damage to the die assembly.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. Die casting apparatus comprising, in combination, a molten metal reservoir; a nozzle communicating with said reservoir and having a discharge aperture; a mouth plate having one surface in heat conductive contact with said nozzle discharge aperture and having an opening .therethrough in alignment with said aperture; a metal mold in heat conductive juxtaposed contact with the other surface of said plate and formed with a mold cavity having an injection opening alignable with said plate opening; a reciprocable ejection pin movable through said injection opening and cavity to eject a casting from said metal mold; a guide mounting said metal mold for movement along and in such juxtaposed contact with said other plate surface between an injection position, in which said inject-ion opening is aligned with said plate aperture, and an ejection position in which said injection opening is aligned with said ejection pin; means operable when said metal mold is in the injection position to move molten metal from said reservoir into said nozzle and to eject the molten metal from said nozzle through said discharge aperture and said plate aperture into said mold cavity; a push rod reciprocable axially in said nozzle and in said discharge aperture and said plate opening, said push rod having an operative position in which an outer conical portion thereof enters and blocks said discharge aperture and a cylindrical extension thereof extends through said plate opening to a position wherein its outer surface is substantially flush with the plane of juxtaposition of said plate and said mold, and a retracted position in which said outer conical portion and cylindrical extension of said push rod are withdrawn from said discharge aperture and said plate opening; means operable to move said push rod to its retracted posit-ion during injection of molten metal into the mold cavity; means operable, responsive to completion of the injection of molten met-a1 into said mold cavity, t move said push rod to its operative position to exclude molten metal completely from said discharge aperture and said plate opening; means operable, when said metal in said mold cavity is cooled and partly solidified, to move said mold along and in the juxtaposed contact with said other plate surface to the ejection position; and means operable, when said mold is in the ejection position to reciprocate said ejection pin through said injection opening and cavity to eject the solidified casting from said metal mold.

2. Die casting apparatus, as claimed in claim 1, including core elements associated with said mold cavity and movable relatively therewith; and means operable, after injection of said molten metal into said mold cavity and before movement of said metal mold to said ejection position, to retract said core elements from said mold cavity.

3. Die casting apparatus, as claimed in claim 1, in which said reservoir is formed with a molten metal passage having an outer end communicating with said nozzle; a bushing mounted Within said passage; said bushing reciprocably mounting said push rod; and means extending through an aperture in the wall of said bushing and engageable with said push rod to operate the same cyclically.

4. Die casting apparatus, as claimed in claim 1, in which said means for moving metal from said reservoir into said nozzle and for ejecting metal from said nozzle comprises a cylinder communicating with the molten metal in said reservoir, a piston in said cylinder, and means for reciprocating said piston.

5. Die casting apparatus, as claimed in claim 4, in which said reservoir is provided with a first molten metal passage having an outer end communicating with said nozzle; a second molten metal passage connecting said nozzle to said cylinder; said piston, when moved in a retracting direction in said cylinder, drawing metal from said receptacle through said molten metal passages and said nozzle into said cylinder and, when moved in the opposite direction, forcing molten metal from said cylinder through said second passage and into said nozzle for injection into the mold cavity; said push rod, in its retracted position, blocking said outer end of said first molten metal passage.

6. A method of die casting without the formation of sprue, runners, or gates, said method comprising the steps of: providing a die with a cavity having neither sprue, runner nor gate portions, with the cavity corresponding solely to the finished external shape of the casting, the cavity including an injection opening through a wall of the die; positioning the die With such wall juxtaposed flush to the surface of a mouth plate having an aperture therethrough, with the die being slidable longitudinally relative to the mouth plate; moving the die, in flush relation with the mouth plate, to a position in which the injection opening is aligned with the aperture in the mouth plate; injecting molten metal through the aperture in the mouth plate into the die cavity under pressure to completely fill the die cavity and force air from the cavity; as the die cavity fills with molten metal, moving a plunger into the aperture of the mouth plate to a position in which the end of the plunger is flush with the surface of the mouth plate engaged by the die wall, to intercept the flow of metal into the cavity and force excess metal backwardly around the plunger; moving the die, with the metal in the cavity partly solidified due to heat extraction by water, to a position in which the injection opening is displaced from the aperture in the mouth plate, while maintaining such die wall flush with the surface of the mouth plate, to detach and remove the partially solidified metal from the plunger at the end surface of the latter flush with the surface of the mouth plate; and thereafter ejecting the solidified casting from the cavity by inserting an ejection member through the injection opening to force the solidified casting out of the die cavity.

References Cited by the Examiner UNITED STATES PATENTS 458,050 8/ 9'1 Hanson 22--70 698,592 4/02 Veeder 22-71 1,005,43 8 10/ 11 LeBoeuf 22-71 I. SPENCE QVERHOLSER, Primary Examiner, 

1. DIE CASTING APPARATUS COMPRISING, IN COMBINATION, A MOLTEN METAL RESERVOIR; A NOZZLE COMMUNICATING WITH SAID RESERVOIR AND HAVING A DISCHARGE APERTURE; A MOUTH PLATE HAVING ONE SURFACE IN HEAT CONDUCTIVE CONTACT WITH SAID NOZZLE DISCHARGE APERTURE AND HAVING AN OPENING THERETHROUGH IN ALIGNMENT WITH SAID APERTURE; A METAL MOLD IN HEAT CONDUCTIVE JUXTAPOSED CONTACT WITH THE OTHER SURFACE OF SAID PLATE AND FORMED WITH A MODL CAVITY HAVING AN INJECTION OPENING ALIGNABLE WITH SAID PLATE OPENING; A RECIPROCABLE EJECTION PIN MOVABLE THROUGH SAID INJECTION OPENING AND CAVITY TO EJECT A CASTING FROM SAID METAL MOLD; A GUIDE MOUNTING SAID METAL MOLD FOR MOVEMENT ALONG AND IN SUCH JUXTAPOSED CONTACT WITH SAID OTHER PLATE SURFACE BETWEEN AN INJECTION POSITION, IN WHICH SAID INJECTION OPENING IS ALIGNED WITH SAID PLATE APERTURE, AND AN EJECTION POSITION IN WHICH SAID INJECTION OPENING IS ALIGNED WITH SAID EJECTION PIN; MEANS OPERABLE WHEN SAID METAL MOLD IS IN THE INJECTION POSITION TO MOVE MOLTEN METAL FROM SAID RESERVOIR INTO SAID NOZZLE AND TO EJECT THE MOLTEN METAL FROM SAID NOZZLE, THROUGH SAID DISCHARGE APERTURE AND SAID PLATE APERTURE INTO SAID MOLD CAVITY; A PUSH ROD RECIPROCABLE AXIALLY IN SAID NOZZLE AND IN SAID DISCHARGE APERTURE AND SAID PLATE OPENING, SAID PUSH ROD HAVING AN OPERATIVE POSITION IN WHICH AN OUTER CONICAL PORTION THEREOF ENTERS AND BLOCKS SAID DISCHARGE APERTURE AND A CYLINDRICAL EXTENSION THEREOF EXTENDS THROUGH SAID PLATE OPENING TO A POSITION WHEREIN ITS OUTER SURFACE IS SUBSTANTIALLY FLUSH WITH THE PLANE OF JUXTAPOSITION OF SAID PLATE AND SAID MOLD, AND A RETRACTED POSITION IN WHICH SAID OUTER CONICAL PORTION AND CYLINDRICAL EXTENSION OF SAID PUSH ROD ARE WITHDRAWN FROM SAID DISCHARGE APERTURE AND SAID PLATE OPENING; MEANS OPERABLE TO MOVE SAID PUSH ROD TO ITS RETRACTED POSITION DURING INJECTION OF MOLTEN METAL INTO THE MOLD CAVITY; MEANS OPERABLE, RESPONSIVE TO COMPLETION OF THE INJECTION OF MOLTEN METAL INTO SAID MOLD CAVITY, TO MOVE SAID PUSH ROD TO ITS OPERATIVE POSITION TO EXCLUDE MOLTEN METAL COMPLETELY FROM SAID DISCHARGE APERTURE AND SAID PLATE OPENING; MEANS OPERABLE, WHEN SAID METAL IN SAID MOLD CAVITY IS COOLED AND PARTLY SOLIDIFIED, TO MOVE SAID MOLD ALONG AND IN THE JUXTAPOSED CONTACT WITH SAID OTHER PLATE SURFACE TO THE EJECTION POSITION; AND MEANS OPERABLE, WHEN SAID MOLD IS IN THE EJECTION POSITION TO RECIPROCATE SAID EJECTION PIN THROUGH SAID INJECTION OPENING AND CAVITY TO EJECT THE SOLIDIFIED CASTING FROM SAID METAL MOLD. 